Senior Kyiv officials said that Ukraine was creating a "buffer zone" in Russia's Kursk region and plans to organise humanitarian assistance and evacuation corridors for civilians looking to go either to Russia or to Ukraine.
President Volodymyr Zelenskiy met with top officials to discuss the humanitarian situation and the possible establishment of military administrations in areas seized by Ukrainian forces in a cross-border assault that began on August 6.
"Our military plan to ... open humanitarian corridors for the evacuation of civilians: both in the direction of Russia and in the direction of Ukraine," Deputy Prime Minister Iryna Vereshchuk said on the messaging app Telegram.
Kyiv plans to arrange access for international humanitarian organisations likely to include the International Committee of the Red Cross and the United Nations, officials said.
"In the buffer zone, food, medicine, and other items necessary for the civilian population should be provided," Ukraine's human rights commissioner Dmytro Lubinets said on Telegram.
Zelenskiy said Ukrainian forces "strictly adhere" to international conventions and humanitarian law.
Ukraine said on Wednesday its cross-border invasion had advanced one to two kilometres in the Kursk region since the start of the day and that its troops had finished clearing the Russian border town of Sudzha of Moscow's forces.
Russian forces have for months been pummelling Ukraine border regions with strikes launched from adjacent territories, including from the Kursk region.
"The creation of a buffer zone in the Kursk region is a step that is designed to protect our border communities from daily enemy attacks," Interior Minister Ihor Klymenko said on Telegram.
Russia's President Vladimir Putin has used the same terminology to refer to new front opened by Russian forces in Ukraine's northeastern Kharkiv region in May.